If its done right then i would play it. I have played on Uniwar, real racing (sorta multiplayer) and dino smash.
I've played mostly online multiplayer games, none of the short range ones as many of my friends don't have iPhone/iPod Touch.
I've played Poker, Tap Tap Revenge, Word Scramble, and a few others. I'd love to try Flight Control on multiplayer, but no-one nearby has an iPhone. I think multi-player over bluetooth is nice, but kind of a regression when compared to multiplayer over wifi & data.